A young onchopristis is essentially a small adult, capable of fending for itself from the moment it hatches. They live largely solitary lives and spend much of their early years hiding in mangroves and reefs. They generally seem to prefer to remain in water with salinity comparable to that they hatched in, though as adults they gain the ability to swim in fresh and salt water. Many fishermen believe it is good luck to return any young onchopristis caught in a river, lest the water grow sour in their absence.

Though relatively common all along the coastline and even far up large inland rivers, onchopristis are seldom seen for their spotted patterns allow them to easily blend into murky water and the ocean floor. They employ a variety of hunting strategies depending on what environment they find themselves in; in rivers, they hunt along the channel digging up creatures hidden in the sand; in reefs, they sweep their long, tooth-lined snouts to spear prey; in more open water, they are surprisingly swift and will chase down individual fish then stun them with a flick of their snouts. They grow relatively large, some reaching lengths of twenty feet or more and require constant food to fill their bellies. Despite their voracious appetites, these creatures only eat fairly small fish and mollusks, and are generally considered harmless to humans.